evaluation of lightning arrestor by using matlab

EVALUATION OF LIGHTNING ARRESTOR BY

USING MATLAB

DISSERTATION

Submitted in partial fulfillment of the requirement for the award of the

degree of

MASTER OF TECHNOLOGY

IN

(Electrical Engineering)

By

GAURAV SHARMA

Under the Guidance of

Mr. ANSHUL MAHAJAN

School of Electrical and Electronics Engineering

Lovely Professional University

Punjab

MAY-2015

ii

CERTIFICATE

This is to certify that the DISSERTATION titled “EVALUATION OF LIGHTNING

ARRESTOR BY USING MATLAB” that is being submitted by “GAURAV SHARMA” is in

partial fulfillment of the requirements for the award of MASTER OF TECHNOLOGY DEGREE

IN ELECTRICAL ENGINEERING, is a record of bonafide work done under my guidance. The

contents of this DISSERTATION,is full or in parts, have neither been taken from any other source

nor have been submitted to any other institute or University for award of any degree or diploma and

the same is certified.

Mr. ANSHUL MAHAJAN

ASSISTANT PROFESSOR

LOVELY PROFESSIONAL UNIVERSITY

DATE:

iii

ABSTRACT

Nowadays, to operate the electrical energy in steady state is the major problem due to the

faults or disturbances occur in the power system. The disturbances occur due to on and off of the

system, lightning occurrences, or due to the symmetrical and unsymmetrical faults. The magnitude

of voltage and current increases as compared to the steady state due to change in circuit conditions

i.e. opening and closing of the switches, or occurrence of a natural fault such as lightning,

discharge.

Maximum overvoltage across the system is due to the overvoltage which affects the steady

state stability of the system and makes the system faulty. When there is overvoltage on the

transmission line it rapidly increases the magnitude of voltage and current in the system and

disturbs the stability of the system due to which system gets switched off. To protect the system

from overvoltage disturbances lightning surge arrestors are used.

In this report we are protecting the system from getting damaged by the overvoltage

developed across the system (due to switching or lightning). For analyzing the system we are

consider two cases of overvoltage i.e. lightning and switching. In this report we emphasize the

impact of protection technique used for protecting the various equipment from overvoltage develop

across the system.

All the simulating work is done in MATLAB/Simulink in which we developed different

graphical relationship between current, voltage waveforms with respect to time. All the simulation

is done by inducing lightning on different points on the transmission line and then comparison is

made, then considering the results by using arrestor model and without using arrestor model. In the

last we concluded that it is preferable to use arrestor across the line to protect the compensated

devices across the system because the arrestor protective device operates immediately in order to

remove the heavy overvoltage to pass through the compensated devices.

iv

ACKNOWLEDGEMENT

I am grateful to the individuals who contributed their valuable time towards my report work. I wish

to express my sincere and heart full gratitude to my DISSERTATION guide Mr. ANSHUL

MAHAJAN, professor in Electrical and Electronics Department, who guides me to took up this

DISSERTATION in sync with global trends in scientific approach.

I thank with the deep sense of gratitude to Mr. ANSHUL MAHAJAN, for his constant

encouragement and cooperation during DISSERTATION for forecasting an excellent academic

environment which made my DISSERTATION work possible. I also thank to HOD, HOS, entire

faculty members and fellow classmates.

I thank with the deep sense of gratitude to my parents, for there constant encouragement and

cooperation which made my DISSERTATION work possible.

GAURAV SHARMA

Reg. No. 11302031

v

DECLARATION

I GAURAV SHARMA, student of M.TECH POWER SYSTEMS under Department of

ELECTRICAL AND ELECTRONICS ENGINEERING of lovely professional university,

Punjab, hereby declare that all the information furnished in this Dissertation report is based on my

own intensive research and is genuine.

This Dissertation does to the best of my knowledge; contain part of my work which has been

submitted for the award of my degree either of this university or any other university without

proper citation.

GAURAV SHARMA

Registration No. 11302031

Date:

vi

TABLE OF CONTENTS

PAGE NO.

CERTIFICATE ii

ABSTRACT iii

ACKNWLEDGEMENT iv

DECLARATION v

LIST OF FIGURES ix

LIST OF TABLES xii

CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION 1

1.2 OVERVOLTAGE 2

1.3 LIGHTNING 2

1.3.1 LIGHTNING FORMATION 3

1.3.2SOME LIGHTNING FACTS 4

1.3.3CHARACTERISTICS OF LIGHTNING STROKES 4

1.3.4 OVERVOLTAGE DUE TO LIGHTNING 5

1.3.4.1 OVERVOLTAGE DUE TO DIRECT LIGHTNING STROKES 5

1.3.4.2 OVERVOLTAGE DUE TO INDIRECT LIGHTNING STROKES 6

1.3.5 LINE DESIGN BASED ON DIRECT STROKES 7

1.3.6 PROTECTION AGAINST LIGHTNING 7

1.3.7 LIGHTNING ARRESTOR 8

1.3.8 CALCULATION OF ARRESTOR VOLTAGE AND CURRENT 9

1.3.9 LIGHTNING PROTECTION OF LOW VOLTAGE INSTALLATION 12

vii

1.3.10 EFFECT OF LIGHTNING CURRENT 12

1.4 SWITCHING OVERVOLTAGES 13

1.4.1 ORIGIN OF SWITCHING OVERVOLTAGES 13

1.4.2 OTHER SWITCHING OPERATION 14

CHAPTER 2

LITERATURE SURVEY

2.1 INTRODUCTION 15

2.2 RELATED WORK 15

2.3 PRESENT WORK 20

CHAPTER 3

WORK DONE

3.1 PROBLEM FORMULATION 21

3.2 OBJECTIVES 21

3.3 TOOLS 22

3.3.1 MATLAB/SIMULINK 22

3.4 RESEARCH METHOLOGY 22

CHAPTER 4

RESULTS AND DISCUSSION

4.1 BASIC DETAILS OF SIMULATING MODEL 29

4.2 SUBSYSTEM USED IN THE MODEL 29

4.3 SIMULATION CRITERIA 31

4.3.1 SWITCHING OVERVOLTAGE 31

4.3.1.1SWITCHING OVERVOLTAGE ACROSS

COMPENSATION DEVICES 31

4.3.2 LIGHTNING OVERVOLTAGE 35

4.3.2.1 OCCURANCE OF LIGHTNING BEFORE

SERIES CAPACITOR 35

viii

4.3.2.2 OCCURANCE OF LIGHTNING AFTER

SERIES CAPACITOR 39

4.4 SIMULATION RESULTS 42

CHAPTER 5

CONCLUSION AND FUTURE SCOPE

5.1 CONCLUSION 47

5.2 FUTURE SCOPE 47

REFERENCES 48

APPENDIX

GLOSSARY OF TERMSS 51

ABBREVIATIONS 52

ix

List of Figures Page No.

1.1 Basic block diagram of overvoltage develop across the system 2

1.2 Representation of lightning formulation in the atmosphere 3

1.3 Represent the characteristics of lightning strokes 4

1.4 Direct lightning strike on the roof of the building 5

1.5 Direct lightning strike on overhead low voltage line 6

1.6 Overvoltage due to indirect lightning 7

1.7 Surge arrester internal structure 9

1.8 The Characteristics of surge arrestor 9

1.9 Surge arrester at the end of a line actual circuit 10

1.10 Surge arrester at the end of a line equivalent circuit 10

1.11 Surge arrester at the junction of two line actual circuit 11

1.12 Surge arrester at the junction of two line equivalent circuit 11

3.1 A single phase MATLAB/Simulink model of switching overvoltages without using

arrestor 23

3.2 A single phase MATLAB/Simulink model of switching overvoltage by arrestor 24

3.3 A single phase MATLAB/Simulink model lightning overvoltage before series capacitor

without using arrestor 25

3.4 A single phase MATLAB/Simulink model of lightning overvoltage before series capacitor

by arrestor 26

3.5 A single phase MATLAB/Simulink model lightning overvoltage after series capacitor

without using arrestor 26

3.6 A single phase MATLAB/Simulink model of lightning overvoltage after series capacitor

by using arrestor 27

3.7 Simulink model of impulse generator 28

4.1 Represent the Voltage Vs Time wave generator which act as

lightning voltage source 30

x

4.2 Represent the Voltage Vs Time wave generator which act as

lightning voltage source 30

4.3 Volatge Vs Time and Current Vs Time waveform of the shunt reactor at

Sending end of transmission line, Switching overvoltage without using

Arrestor 32

4.4 Volatge Vs Time and Current Vs Time waveform of the series capacitor at

Midpoint of transmission line, Switching overvoltage without using

Arrestor 32


Receiving end of transmission line, Switching overvoltage without using

Arrestor 33


Sending end of transmission line, Switching overvoltage by using

Arrestor 34

4.7 VolatgeVs Time and Current Vs Time waveform of the series capacitor at

Midpoint of transmission line, Switching overvoltage by using

Arrestor 34

4.8 VolatgeVs Time and Current Vs Time waveform of the shunt reactor at

Receiving end of transmission line, Switching overvoltage by using

Arrestor 34


Sending end of transmission line, lightning overvoltage before

series capacitor without using arrestor 36


midpoint of transmission line, lightning overvoltage before



receiving end of transmission line, lightning overvoltage before


xi


Sending end of transmission line, lightning overvoltage before

series capacitor by using arrestor 38


midpoint of transmission line, lightning overvoltage before



receiving end of transmission line, lightning overvoltage before



Sending end of transmission line, lightning overvoltage after



midpoint of transmission line, lightning overvoltage after



receiving end of transmission line, lightning overvoltage after


4.18 A single phase MATLAB/Simulink model of 735KV transmission system

Feed a load through a 200Km transmission line, lightning overvoltage

After series capacitor by using arrestor 41


Sending end of transmission line, lightning overvoltage after



midpoint of transmission line, lightning overvoltage after


xii

LIST OF TABLES PAGE NO.

1.1 Method adopted for protecting the electrical equipment from lightning strokes 8

4.1 Switching overvoltage without using arrestor 32

4.2 Switching overvoltage by using arrestor 33

4.3 Lightning overvoltage before series capacitor without using arrestor 36

4.4 Lightning overvoltage before series capacitor by using arrestor 37

4.5 Lightning overvoltage after series capacitor without using arrestor 39

4.6 Lightning overvoltage after series capacitor by using arrestor 41

4.7 Comparison between switching overvoltage with arrestor and without

arrestor model 42

4.8 Comparison between lightning overvoltage before series capacitor

with arrestor and without arrestor model 44

4.8 Comparison between lightning overvoltage before series capacitor

with arrestor and without arrestor model 45

1

CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION

Overvoltage is one of the major problem occurring in the power system and to

minimise this problem many methods, equipment’s and techniques have used. It is of two

types i.e. lightning and switching. To improve the performance of the power system from

lighting several studies has been conducted and many methodologies have been proposed in

the technical literature over the last decades. The most important safeguard in electrical

power system is to protect overhead high voltages transmission line from lightning strokes.

Accurate evaluation of the lightning performance helps to make the system highly efficient.

Shield wires and surge arrestors are used for the protection of lines from lightning. Due to the

lightning phenomena overvoltage occurs which reduces the reliability of electrical network,

leading to interruption and as a consequence increases the transmission line repair cost. To

minimize the annual failure of the line overhead ground wires are placed above the phases to

intercept lightning strokes[2] . Surge arrestors are the main measures, which are used in order

to protect the system against lightning and switching phenomena.

Franklin‟s invention of lightning rod to be protects apparatus from lightning strikes.

Till today for more than 200 years, the lightning rod has been used for air terminal of

lightning protection systems [6] But lightning rods cannot always function perfectly because

they have an unexpected shielding failures, are often due to the improbability of lightning

phenomenon. For example, several direct strikes to the transformer substations took place in

the power grid of north India. For designing a lightning protection system, the protection

angle method, the rolling sphere method and the mesh method are used to evaluate the

protection zone of a lightning rod, all of these fall considerations on stochastic behaviours of

the lightning process. The effectiveness of lightning rods is investigated by means of dynamic

simulation of lightning strikes including stochastic [19].

Over voltages in the power system may be due to the lightning strokes that terminate

on or near to power lines such over voltages are known as lightning over voltage or surges.

Switching over voltages or surges is due to the certain change in the circuit condition brought

2

about by deliberate or unintentional switching operation[15]. The magnitude of lightning over

voltage is essentially independent of system voltage is known as external over voltages.

1.2 OVERVOLTAGE

When the voltage across the system increased to very high value than its normal voltage

flowing in the system, the increased voltage which is beyond the upper limit of voltage across

the system is known as overvoltage. The overvoltage is one of the most dangerous condition

arises across the system. The overvoltage across the system depends on duration that whether

it’s a transient or a voltage spike or permanent [16]. There are two types of overvoltage occur

in the system.

Natural: - The natural source of overvoltage is lightning.

Man-made:-Man made source of overvoltage usually caused by switching

Figureure1.1Basic block diagram of different overvoltage develop across the system

1.3 LIGHTNING OPERATION

Lightning is a phenomenon that occurs in nature. The energy contained in a lightning

stroke is very high and it can be tremendously destructive. Lighting strokes are unprotected to

electric distribution networks. A single stroke to a distribution line is sufficient to cause a

OVERVOLTAGE

INTERNAL EXTERNAL

SWITCHING

OPERATION

LIGHTNING

OPERATION

DIRECT

LIGHTNING

INDIRECT

LIGHTNING

TIME FRAME

to

TIME FRAME

to

3

blackout throughout a feeder and to prevent this type of problems power systems are

protected with lightning rods, ground wires and lightning arrestors. Overhead high voltage

transmission lines and to reduce the failure rate, arrestors are installed between each phase

and earth to protect the system [2].

1.3.1 LIGHTNING FORMATION

Lightning formation is the technique which develops, when there is charge separation

in the clouds. Lightning is static charges which develop across the system just like a static

charge develops when a balloon is rubbed and produce static electricity [6].

Figureure1.2Representation of lightning formulation in the atmosphere

Once a significant charge separation has built up the positive and negative charges

seek to reach each other and neutralize. Streamers come up from the ground to form a

pathway. Once a pathway is completed a spark forms and neutralizes the charge. As the

negative charge races down, the air surrounding gets heat up. The spark is very hot and it

rapidly heats the air to create a shock wave [6].This shock wave is known as lightning.

4

1.3.2 SOME LIGHTNING FACTS

There are 100 lightning strikes a second happening worldwide.

There are more than 8lakh lightning bolts per day.

Lightning flash is about 4.5 Km long but only a centimetre wide

A lightning strike discharges about 1-10 lakhs joules of energy and produces a current

of 30,000 to50,000 amperes.

A single lightning bolt has as much energy as blowing up a ton of TNT.

1.3.3 CHARACTERISTICS OF LIGHTNING STROKES

Lightning strokes characteristics are studied by investigating a large number of aspects:-

Lightning strokes are of negative polarity.

Total surge report occur in the power system are7 to 18% strokes on transmission

lines,37% distribution lightning arrestor surges and 12% station lightning arrestor

Time taken by a lightning stroke may be 1 sec or so.

A lightning stroke may contain peak current from 1kA to 200kA or so. Figure1.1

shows the distribution of peak value of lightning current.

The time to first peak is between zero and 10 microseconds. The time to half value on

the tail is between 5 and 90 microseconds [6].

Figureure1.3 Represent the characteristics of lightning strokes

5

1.3.4 OVERVOLTAGE DUE TO LIGHTNING

When the lightning occurs in the system the voltage develops across the system

becomes too high. Basically lightning is a natural phenomenon in which voltage value may

be high and low energy level. The direct lightning strike on the conductor or roof of the

system it will damage the system or equipment being installed in the system. The over

voltage develops across the system is more than the 20 times the normal voltage develop

across the system which harms the rating of the equipment being installed in the system. The

over voltage may be due to direct lightning strokes or may be indirect lightning strokes[6].

1.3.4.1 OVERVOLTAGE DUE TO DIRECT LIGHTNING STROKES

These can be in two forms:

When lightning strike the conductor:- When lightning strikes on the lightning

conductor or on the roof of a building which is earthed or grounded, the lightning

current goes into the ground through the ground wire. The impedance of the ground

and the current flowing through the conductor develops large potential difference, this

is overvoltage. This overvoltage then propagates throughout the building all the way

through the cables and damaged the equipment present in the system.

Figure1.4 Direct lightning strike on the roof of the building

6

When lightning strike on line:-When lightning strikes on overhead low voltage line

it conducts high currents which passes into the building creating large overvoltage.

The damage caused by over voltage is usually very hazardous and results in

explosions [6].

Figure1.5 Direct lightning strike on overhead low voltage line

1.3.4.2 OVERVOLTAGE DUE TO INDIRECT LIGHTNING STROKES

The lightning current generates the electromagnetic field across the system due to

which the capacitive and inductive coupling develops the over voltage across the system.

Basically over voltage develops when lightning strikes on the conductor or in the building

this is due to the higher potential of ground at the point of impact [6]. The energy contained

in a lightning stroke is very high and it can be tremendously destructive. Lighting strokes are

defenceless to electric distribution networks. A single stroke to a distribution line is sufficient

to cause a blackout throughout a feeder and to prevent this type of problems in power systems

are protected with lightning rods, ground wires and lightning arrestors. To reduce the failure

rate across overhead high voltage transmission lines arrestors are installed between each

phase and earth to protect the system

7

Figure1.6 Overvoltage due to indirect lightning

1.3.5 LINE DESIGN BASED ON DIRECT STROKES

The basic principles to protect system from direct lightning strike are:

There should be supply with ground wire of sufficient mechanical strength to shield

the phase conductors from direct lightning strokes.

There must be adequate clearance from the phase conductor to the tower so that full

effectiveness of the insulating structure can be obtained.

There must be adequate clearance from the phase conductor and the ground wire

especially at mid span so that flashover between phase conductor and ground wire are

eliminated

The tower footing resistance should be as low as economically justified. A tower

footing resistance helps in maintaining the tower top voltages to a safe value[3].

1.3.6 PROTECTION AGAINST LIGHTNING

Lightning produces high magnitude of current and voltage in the system. So to protect the

electrical equipment from being damaged from lightning stroke following techniques are to

be studied:-

Transmission line protection from direct lightning strokes.

Substation and power station protection from direct lightning strokes

8

Electrical equipment’s protection from travelling waves flowing in the system.

There are different methods adopted for protecting the electrical equipments from lightning

strokes. These are specified by the types of the lighting strokes come across the system[17].

Table1.1 Methods adopted for protecting the electrical equipment from lightning strokes

S.No. Phenomena Protective Equipment

1 Direct Lightning stroke Ground wire and Lightning arrestors

2 High Voltage Impulse having a step

wave front

Ground wire and lightning arrestor

3 Arcing ground Neutral earthing

4 Low voltage high frequency

oscillations

Condensers or surge absorbers

5 Static over potential Water jet earthing resistance or

earthing choking coils

1.3.7 LIGHTNING ARRESTOR

A lightning arrestor is a device installed near the end of any conductor which is long

enough before the conductor lands on electrical equipment. It’s main purpose is to divert

lightning-induced transients safely to ground through property changes to its varistor in

parallel arrangement to the conductor inside the unit which is also called a surge protection

device or transient voltage surge suppressor, they are only designed to protect against

electrical transients resulting from the lightning flash, not a direct lightning termination to the

conductors [15]. Figure1.7 shows the internal structure of the arrestor. The arrestor consist of

spare gap with non-linear resistor combined and then placed it to earth directly. Lightning

arrestor due to this property act as insulated during normal operation and it act as conductor

when high voltage appear across the system. Figure1.8 is voltage Vs current characteristics of

surge arrestor.

9

Figure 1.7 Surge arrestor internal structure

Figure 1.8 The Characteristics of surge arrestor

1.3.8 CALCULATION OF ARRESTOR VOLTAGE AND CURRENT

ARRESTOR AT THE END OF A LINE

An arrestor connected at the end of the line of surge impedance 𝑍𝑐 and a wave 𝑒𝑓 travelling

on the line.

10

Figure 1.9 Surge arrestor at the end of a line actual circuit

Figure 1.10 Surge arrestor at the end of a line equivalent circuit

Figure1.9 shows the surge arrestor at the junction of a line actual circuit. This is the

basic diagram of arrestor installation in parallel to lines for protecting the system from being

damaged. Figure1.10 is the equivalent circuit of the actual circuit of arrestor installation for

calculating the current present across the arrestor installed in the system.

𝑒 𝑒 𝑍 ---------------1.1

𝑒 -----------------------1.2

Where 𝑒 forward voltage, 𝑒 arrestor voltage, 𝑍 surge impedance,

Arrestor current

11

ARRESTOR AT JUNCTION OF TWO LINES

Arrestor at the junction of two lines having surge impedances 𝑍1 and 𝑧2

Figure 1.11 Surge arrestor at the junction of two line actual circuit

Figure 1.12 Surge arrestor at the junction of two line equivalent circuit

Figure1.11 shows the surge arrestor at the junction of two line actual circuit. This is

the basic diagram of arrestor installation in the system between the two lines for protecting

the system from being damaged. Figure1.12 is the equivalent circuit of the actual circuit of

arrestor installation for calculating the current present across the arrestor installed in the

system.

𝑒 𝑒 𝑍 ----------------- -1.3

𝑒 𝑒 𝑍

---------1.4

𝑒 𝑒 (

) 𝑍 --------1.5

𝑒 ------------------------1.6

12

Where 𝑒 forward voltage, 𝑒 arrestor voltage, 𝑍 surge impedance,

Arrestor current, 𝑍 surge impedance of line 1

𝑍 Surge impedance of line 2

In the above equations the surge impedance plays a very important role in limiting the

voltage across the arrestor. If 𝑍𝑐 and 𝑍1 = 0 i.e. line is absent, the voltage 𝑒𝐴 is equal to2𝑒𝑓.

An arrestor as a separate entity does not limit the voltage. It is only through the combination

of arrestor characteristics and line surge impedance that we can limit the voltage across the

equipment [6].

1.3.9 LIGHTNING PROTECTION OF LOW VOLTAGE INSTALLATION

Lighting can cause huge damage to low voltage installation. These installations

include towering buildings, communication lines, equipment’s and other similar facilities.

Lighting may travel on power lines and enter these installations through power lines.

Lightning protection scheme involves five basic steps:

It Capture the lightning stroke through an air terminal

The system Conduct the lightning current to earth through a down conductor

Scatter energy of lightning stroke allows impedance earthing system

It avoid earth loops and potential differentials

It protect the equipment’s installed from surge travelling on power lines

1.3.10 EFFECT OF LIGHTNING CURRENT

The following effects are noticed if we select and place wrong arrestor in the system.

Thermal effects: When there is lightning the system get heated up due to the increase

in the current in the system. Sometimes it catches fire when the value of current

increases.

Electrodynamics effects: The attraction and repulsion force present in the system

current increases, due to which the wire of the system breaks.

Combustion effects: The shock waves present in the system are transformed into

sound waves which are being heard by us as the sound of thunder. This thunder effect

produces combustion effect in the system.

13

This explains indirect strokes of lightning increase voltage and the breakdown of

equipment. This effect ledS to physical and catastrophic failures initiating industrial/domestic

fire outbreaks, equipment failure, loss of lives and downtime revenue loss and not only make

the system discontinuous but create other losses also.

Hence it is important to understand damage caused due to lightning and provide best

protection against lightning hazard using international standards.

1.4 SWITCHING OVERVOLTAGES

Another method of overvoltage occurrence in the system is switching operation. The

increase in transmission voltage needs to fulfil the requirement of increase transmission

powers, switching surges have become the main factor for designing of insulation for the

transmission line. In the meantime the lightning overvoltage which is a source of external

overvoltage develops across the system comes as a secondary factor in the transmission line

protection [1]. There are two fundamental reasons for this shift in relative importance from

lightning surges as higher transmission voltages are called for:

Over-voltages developed on the transmission line by lightning strokes are only

slightly dependent on the power system voltages. As a result of this the magnitude

relative to the system peak voltage decrease as later it increase.

External insulation has breakdown strength lowest under surge whose fronts fall in the

range 50-500 micro sec. which is typically for the switching surges develop in the

system.

1.4.1 ORIGIN OF SWITCHING OVERVOLTAGES

There are many methods or faults occur in the system due to which the switching

operation takes place. The origin of such over-voltages develop across the system cause

various type of disturbances in the system and make the system faulty to work in the strong

condition.

The various types of switching operations develop across the system are:

ENERGIZATION OF TRANSMISSION LINES AND CABLES:- The specific

switching operation occur in this category which makes the system faulty are:

14

a. Energization of a line that is open circuited at the far end

b. Energization of a line that is terminated by a unloaded transformer

c. Energization of a line through the low voltage side of the transformer

RE-ENERGIZATION OF THE LINE:- Re-energization of the line means the

energization of the line carrying charge get trapped by previous line interruptions

when high speed recloures are used.

LOAD REJECTION:- This is affected by the circuit breaker opening at the far end

of the line. This is also be followed by opening the line at the sending end which is

also known as the line dropping operation.

SWITCHING ON AND OFF OF THE EQUIPMENTS:- All switching operations

involving an element of the transmission network will produce a switching surge in

the system and makes the system faulty. The switching surge develop across the

system by:

a. Switching of high voltage reactors

b. Switching of transformers that are loaded by a reactor on their tertiary

winding.

c. Switching of transformer at no load.

1.4.2 OTHER SWITCHING OPERATIONS

Reclosing (energization of a line with trapped charges)

Energization of a line terminated by an unloaded transformer

Load rejection at the receiving end of a line

Load rejection at the receiving end of the line followed by line dropping at the

sending end

Interrupting lines at no-Load of transmission line (line dropping)

Switching of transformers at no-load

Initiation of a single phase to earth fault without a switching operation

15

CHAPTER 2

LITERATURE SURVEY

.1 INTRODUCTION

In the literature survey different topic related to overvoltage protection mainly topics are

on the overvoltage due to lightning occurrence in the system and switching operation. In

literature survey various journals and conference topic related to the lightning protection and

the techniques used by various authors to predict the lightning faults or failure occur due to

lightning in the system.

2.2 RELATED WORK

D.RODRIGUEZ SANABRIA, C.RAMOS ROBLS AND L.ORAMA EXCLUSA (2006)

In this paper the author present how ATP/EMPT plays an important role to model

lightning strikes and what are the various effect of lightning on power distribution system.

Mainly the research is done on the action and development of arrestor used in the system. In

this paper the author analyse the effect of lightning strike and multiple lightning strokes are

simulated in ATP. The author monitored the effect of direct lightning strike on the substation

buses and voltage buses across the system. In this paper the author not only work on ideal

system but also simulate the result on worse conditions also.

L.EKONOMOU, I.F.GONOS, I.A.STATHOPULOS (2006)

In this paper the author work on the artificial neural network (ANN) method to

develop a model based on the lightning performance of high voltage transmission line in the

power system. The main advantage of this system is that the author uses ANN method to

simulate the output result by taking actual data. Nowadays ANN method is most economical

and efficient method as compare to the other computer technologies. ANN method is being

used in the transmission line with similar characteristics as that of the transmission line. This

method is used in training and testing procedure for taking desirable results. In this paper the

author use the radial basis and feed-forward ANN methods, in which transfer function and

structure is calculated for carrying out the desire result accurately. The author compares

16

advantages and disadvantages of the ANN methods and proposed the ANN is best method for

the design of the electrical power system.

DALINA JOHARI, TITIK KHAWA ABDUL RAHMAN (2007)

In this paper the author is predicted the lightning occurrence by using ANN method

and compare it to the other forecast techniques available in the system. The author uses the

historical data and the meter logistic data to make the ANN method efficient to predict the

lightning occurrence in the system. The author got successful after teste the data on the

different networks. The author got the desired result by using a heuristic technique.

C.A.CHRISTODOULOU, G.PERANTZAKIS, G.E. SPANAKIS AND

P.KARAMPELAS (2008)

In this paper the author uses artificial neural network method in which he specially

work on the Q-learning algorithm for the high voltage transmission line for evaluating the

lightning performance. In this paper the author make result of lightning failure rate without

arrestor as well as the probability of arrestor failure. The result of various simulations is done

by appropriate tools in the system. The ANN method is best reliable, small size, quick

training process and consumes less memory as compare to other system.

YONG WANG, JIN CHANG ZHOA, GUI FANG ZHANG (2008)

In this paper the author model a 10KV transmission line in which he placed surge

arrestor. The author also works on the basic surge arrestor principle and its working

procedure. The author analyse the result by using different cases and different number of

arrestors by using PSCAD. The author concludes that the usage of surge arrestor can reduce

the large amount of current flowing in the system and over voltage develop across the line. It

is the best economical and effective way to protect the system from being damage by

lightning strokes.

17

XUEWEI ZHANG, LIN DONG, JINLIANG HE, SHUIMIMG CHEN AND ROG

ZENG (2009)

In this paper the author did series simulation of single lightning rod. The author shows

how we are able to protect the system from being damaged by the lightning so he has done

various simulations on various lightning rods and verified that the system is capable to

protect the power system from lightning occurrence in the system. The author conclude about

the topic that, Interception area of the system is directly proportional to the rod augments

height, The upper section of the rod is relatively denser due to the strike distribution,

Lightning protection zone are analysis by using different rod height and The protection zone

sharper, as the height of the rode increases.

M.A. OMIDIORA (2009)

In this paper the author discussed about the performance of overvoltage develop due to

real lightning discharges occurring in distribution power lines equipped with covered

conductors. The author evaluates and simulates the results based on real lightning data

collected from the Finnish Meteorological Institute (FMI). Evaluation of induced overvoltage

from indirect stroke to the line is analysed with MATLAB and various results has been

concluded. With the Electromagnetic Transient Program (EMTP), simulations of lightning

strokes are performed with different lightning current characteristics and then all cases are

considered with the modelling guidelines as specified in some lightning literature.

Simulations are made to compared the resulting over-voltages and energy absorptions of

surge arrestors for all the analysed cases. The following remarks are drawn from the study:

The induced voltage due to a lightning stroke to a power line support is more intense

than the induced voltage due to a lightning stroke to ground.

The distortion increases with the change in lightning characteristic does not lead to a

significant change in the maximum induced voltage for a lightning stroke to a line

support, as was the case for a lightning stroke to ground.

The induced voltage on the distribution line is higher than the induced voltage on the

covered conductor as simulated by the model. This can be very stressful for surge

protective devices.

18

The rate of rise of lightning current decreases as the arrestor dissipation energy

increases.

MICHAEL A.OMIDIORA, MATTI LEHTONEN (2009)

In this paper the author studied the performance of an MV underground cable due to a

nearby lightning discharge occurring in the system. The simulation is made with Finite

Element Method (FEM). In this paper the author consider the effects of lightning stroke

location, resistivity of the soil and underground cable configurations as its primary parameter

and carry out the desirable result .The results of the numerical computation show about

electric field intensity and potential distribution vary with the factors mentioned above.

Estimations of the failure rate of the underground cable are made based on the real lightning

statistics. It is expected that the results will provide a good understanding of the need for

lightning protection on MV underground cables.

ABDOLAMIR NEKOUBIN (2011)

In this paper the author checked the behaviour of fixed series compensated extra high

voltage transmission lines during faults is simulated in the transmission system. While the

need for more compact and environmentally robust equipment is required. Use of series

capacitors for compensating part of the inductive reactance of long transmission lines

increases the power transmission capacity. Emphasis is given on the impact of modern

capacitor protection techniques (MOV protection). The author simulates the performance

using MATLAB/SIMULINK and results are given for a three phase and a single phase to

ground fault. In the last author concluded that during a three phase fault the MOV protection

devices operate immediately, in order to remove the capacitor banks from the system.

The capacitor is not isolated from the line so its reinsertion is instantaneous. An important

result is that as soon as the bypass switch closes the line current is reduced to a value, as if

there were no capacitor banks in the system. During single phase fault only protection

equipment of faulted phase function whiles the capacitor banks of the other phases remain in

the system to maintain stability. And he also concluded that the MOVs’ absorption of energy

is measured in all phases and the energy is exchanged between the capacitor and the MOV.

19

M.CHANAKA, KUSUM SHANTHI, RANJIT PERERA (2011)

In this paper the author carried out a case study on 220KV transmission line at hilly

area of the Sri Lankan. The author works on the lightning back flash over which lead to the

system failure. The author uses the PSCAD software for modelling the system and simulating

the result. The author simulates the result by using the lightning arrestor and without using

the arrestor. The main objective of the paper is to analysis the back flash over and to analysis

the performance of the 220KV line where this system has been installed. In the last the author

concluded that we have to install the lightning arrestor across each tower to protect the

system from lightning develop across the system. So the author does simulation work by

using arrestor and without using arrestor and carry out the various results that how system

behaves.

GU DINGXIE, DAI MIN, HE HUIWEN (2011)

In this paper the author worked on the shielding failure flash over across the system in

the mountainous area. The shielding angle increased with the ground slope along the line in

mountainous area. In this paper the author design a new method and principle for calculating

the inrush over voltage to ultra-high voltage and also make a concept of reducing the

lightning current and shielding failure and optimize the various result of lightning arrestor to

restrict lightning inrush over voltage to the various substation. With the help of this work the

author wants to minimise the amount of MOAs used in the system.

G.E.CHATZAROKIS, V.VITA, P.KARAMPALAS AND L.EKNONOMOUS (2011)

In this paper the author uses artificial neural network method in which he specially

work on the Q-learning algorithm for the high voltage transmission line for evaluating the

lightning performance. In this paper the author make result of lightning failure rate without

arrestor as well as the probability of arrestor failure. The result of various simulations is done

by appropriate tools in the system. The ANN method is best reliable, small size, quick

training process and consumes less memory as compare to other system.

20

VLADIMIR A.RAKOV (2012)

In this paper the author says that the Traditional lightning parameters needed in

engineering applications include lightning peak current, average current rate of rise ,

maximum current derivative (di/dt), current rise time, current duration, action

integral(specific energy) and charge transfer(specific energy), all derivable from direct

current measurements. Distributions of these parameters nowadays adopted by lightning

protection are largely based on measurements. The author wanted that direct current

measurements on instrumented towers were made in other countries. Triggered-lightning

experiments have provided considerable insight into natural lightning processes.

JOHN TARILANYO AFO (2013)

In this paper the author studied about the surge diverters and the performance and

construction of diverters. The author engrossed that the ZnO arrestor has good performance.

The use of arrestor depends upon the life span and efficiency of the diverter used in the

system to protect the system. The author concluded that the rainfall in the atmosphere as well

as dust particles is the main factors which affect the performance of the system.

2.3 PRESENT WORK

Till now the literature survey of different authors about the lightning occurrence in the

system and the different steps taken by them to protect the transmission line from lightning

occurrence. By reading all these paper concluded that there is need to design a system which

can protect the compensated devices attached with the system to protect the highly sensitive

component from overvoltage developed due to lightning and switching.

21

CHAPTER 3

WORK DONE

3.1 PROBLEM FORMULATION

In our dissertation work, we have done literature survey and then design a new model

on lightning arrestor using MATLAB/Simulink. All results and response is carried out in the

MATLAB/Simulink and the performance of the system is noted. The main aim of this system

is to protect the system from heavy damage caused by the over voltages develop across the

system due to lightning and switching, to protect the compensated devices connected across

the system.

We are analysing the behaviour of the current and voltage magnitude developed

across the transmission model by inserting the overvoltage faults such as switching and

lightning. All the simulation work is done by using MATLA/Simulink software in which we

develop the graphical representation between voltage vs time and current vs time waveforms

across the conductor used in the system. All the simulation work is done by using arrestor

and without using arrestor. Then we carried out the results by comparing the two models.

3.2 OBJECTIVES

The objectives of the study of this dissertation work is given as

The main objective of research work is to protect the compensated devices from being

damage from overvoltage occurrence in the system.

To analyse the performance of the system with or without using arrestor in the system

To study the use of surge arrestors across the system and to analyse the result and

graphical representations of voltage vs time and current vs time waveforms of the

conductor affecting the system by using MATLAB/Simulink software.

22

3.3 TOOLS

The tool required for calculating the desired results is

3.3.1 MATLAB\Simulink

Simulink is a block diagram situation for multi area simulation and Model-Based

Scheme. It provisions simulation, automatic code generation, and incessant test and

corroboration of embedded systems. Simulink offers a graphical editor, customizable block

libraries, and solvers for displaying and simulating dynamic systems. It is united with

MATLAB which allowing joining MATLAB algorithms into models and transfer simulation

results to MATLAB for further analysis.

Capabilities

Building the Model: - Model ranked subsystems with predefined library blocks.

Simulating the Model:-Simulate the dynamic performance of system and opinion

results as the simulation runs.

Analysing Simulation Results:-View simulation consequences and restore the

simulation.

Managing Projects:- Easily accomplish files, components, and large amounts of data

for projects.

Connecting to Hardware:-Connect model to hardware for real-time testing and

embedded system deployment.

3.4 RESEARCH METHODOLOGY

To evaluate the performance of lightning arrestor across the overhead transmission line to

protect the system from overvoltage such as lightning and switching develop across the

system, we have used the MATLAB/Simulink as the key software for budding the

comparison between the models with and without the arrestor present in the system. In our

dissertation we construct a 735KV equivalent transmission system by feeding a load through

23

200 Km transmission line. The line is series compensated at the middle of the transmission

line and shunt compensated at the receiving and sending end respectively. A switching as

well as lightning fault is applied to the transmission line to carry out the various simulation

results regarding the fault develop across the system. We are using MATLAB/Simulink to

check the variation of current and voltage develop across the system with respect to time.

Through this research methodology we come to know that which system is best suitable in

the transmission system and what are the various factors effecting the transmission line

caused due to over voltages[1][9].

The series capacitor and shunt inductor are both protected by metal oxide varistors

(MOV). The series capacitor varistor MOV consists of 30 columns protecting the

capacitor at 2.5 times its rated voltage (rated voltage is obtained for a 2000 kA line

rated current). The corresponding protection voltage (defined at 15 kA = 500 A per

column) is 2.5*26.2 *2kA*sqrt(2) = 185 kV.

The shunt inductor is protected by a 2-column arrester (MOV2) at 1.8 p.u. of nominal

phase-to-ground voltage (424.4 kVrms). The corresponding protection voltage

(defined at 1 kA or 500A /column) is 1.8*424.4*sqrt(2) = 1080 kV.

A 3 phase short circuit level of the transmission system is 15000MVA. The line is

40% series compensated by the capacitor and shunt compensated by 330MVar

inductor at the load end. The series capacitance and shunt inductor are protected by

the metal oxide varistor. The series capacitor varistor MOV1 consist of 30 columns

protecting the capacitor at 2.5 times its rated value. The shunt inductor is protected by

a 2 column arrestor at 1.8 pu of nominal phase to ground voltage

SWITCHING MODEL WITHOUT USING ARRESTOR

Figure3.1 A single phase MATLAB/Simulink model of switching overvoltage without using arrestor.

24

In switching overvoltage near the load without using arrestor, the transmission is having

only the shunt and series compensated device. The extra high voltage will pass to ground

through these devices and will affect the compensation system. Due to the high voltage

develop across the system there is large amount of voltage and current flow through the series

and shut compensated system which may even burn the compensated devices and damage the

whole transmission system.

SWITCHING MODEL BY USING ARRESTOR

In this case we use metal oxide surge arrestor to minimize the current and voltage flow

across the compensation line which cause a harmful effect to the transmission line. In this

case an earth to ground fault is inserted inside the system which act as switching operation,

due to which the overvoltage develop across the system.

Figure3.2 A single phase MATLAB/Simulink model of switching overvoltage by using arrestor.

25

OCCURANCE OF LIGHTNING BEFORE SERIES CAPACITOR

WITHOUT ARRESTOR

In this case when lightning will fall before the series capacitor on the transmission line

there is no arrestor present in parallel to the shunt and series compensated device. All

lightning overvoltage will pass though the compensated devices attached across the system.

Figure3.3 A single phase MATLAB/Simulink model of lightning overvoltage before series capacitor without

using arrestor.

OCCURANCE OF LIGHTNING BEFORE SERIES CAPACITOR

BY USING ARRESTOR

In this case when the lightning will fall before the series capacitor, the arrestor installed in

parallel to the shunt and series compensation devices protect the system from the heavy

voltage develop across the system. When the lightning impulse will fall on the transmission

line, the system will produce a back flash to the receiving end and ground the large amount of

lightning voltage to the ground and save the system from heavy damage.

26

Figure3.4 A single phase MATLAB/Simulink model of Lightning overvoltage before series capacitor by using

arrestor.

OCCURANCE OF LIGHTNING AFTER SERIES CAPACITOR

WITHOUT USING ARRESTOR

Figure3.5 A single phase MATLAB/Simulink model of lightning overvoltage after series capacitor without

using arrestor.

27

In this case when lightning will fall after series capacitor on the transmission line there is

no arrestor present in parallel to the shunt and series compensated device. All lightning

overvoltage will pass though the compensated devices attached across the system.

OCCURANCE OF LIGHTNING AFTER SERIES CAPACITOR

BY USING ARRESTOR

In this case when the lightning will fall after the series capacitor, the arrestor installed in

parallel to the shunt and series compensation devices protect the system from the heavy

voltage develop across the system. When the lightning impulse will fall on the transmission

line, the system will produce a back flash to the receiving end and ground the large amount of

lightning voltage to the ground and save the system from heavy damage.

Figure3.6 A single phase MATLAB/Simulink model of Lightning overvoltage after series capacitor by using

arrestor

SUBSYSTEM USED IN THE SYSTEM

In our model we have develop the artificial lightning by using the impulse generator.

From this experiment we investigated that we can obtain the desired impulse voltages and

wave shapes from an impulse voltage generator for high voltages just like the lightning

occurrence in the system. The impulse voltage generated by the impulse generator is

28

4.831* volts which act as external lightning source occurring in the system [1][12].

Impulse voltage generator can be developed by MATLAB Simulink with standard blocks

available in Simulink as shown in Fig. 7. The single-stage impulse voltage generator acting as

lightning source is simulated with the software. The stage sphere gaps were simulated by the

use of switches, as shown. In the case of multistage system, each of the stage capacitors was

given an initial charge voltage value, which is equal to 1/n of the total kV test voltage. The

values of front and tail resistors, as well as the stage capacitors, are the same as used in the

actual impulse generator. The impulse wave forms generated from MATLAB/Simulink

model with different front and tail resistor[11][12]

Figure3.7 Simulink model of impulse generator

29

CHAPTER 4

RESULTS AND DISCUSSION

4.1 BASIC DETAILS OF THE SIMULATIMG MODEL

In our model we have constructed a 735KV equivalent transmission system feed a

load through a 200 Km transmission line. The transmission line is series compensated at the

middle point and shunt compensated at the sending end and the receiving end of the system.

An overvoltage fault is applied to the transmission line. Firstly we apply lightning fault in

which we induce the pulse wave in the transmission line of very high value and then calculate

the various results. This lightning is fall on the different position on the transmission line to

analysis the result of arrestor across the system. Secondly we introduce switching fault near

the load terminal. This fault is cleared by load breaker opening. For simplification purpose

only one phase of the transmission system is modelled. All parameters correspond to positive

sequence

A 3 phase short circuit level of the transmission system is 15000MVA. The line is

40% series compensated by the capacitor and shunt compensated by 330MVar inductor at the

load end. The series capacitance and shunt inductor are protected by the metal oxide varistor.

The series capacitor varistor MOV1 consist of 30 columns protecting the capacitor at 2.5

times its rated value. The shunt inductor is protected by a 2 column arrestor at 1.8 pu of

nominal phase to ground voltage[1][9].

4.2 SUBSYSTEM USED IN THE MODEL

In our model we have develop the artificial lightning by using the impulse generator.

From this experiment we investigated that we can obtain the desired impulse voltages and

wave shapes from an impulse voltage generator for high voltages just like the lightning

occurrence in the system. The impulse voltage generated by the impulse generator is

4.831* volts which act as external lightning source occurring in the system [1][12].

An impulse generator essentially consists of a capacitor which is charged to the

required voltage and discharged through a circuit. The waveform is the standard 1.2/50µs

duration with the peak voltage reached in 1.2µs (T1) and the tail of the wave decaying to a

level of 50% of the peak in 50µs (T2).The circuit parameters can be adjusted to give an

30

impulse voltage of the desired shape. Basic circuit of a single stage impulse generator where

the capacitor Cs is charged from a dc source until the spark gap G breaks down. The voltage

is then impressed upon the object under test of capacitance Cb. The wave shaping resistors

Rd and Re control the front and tail of the impulse voltage available across Cb respectively.

Overall, the wave shape is determined by the values of the generator capacitance (Cs) and the

load capacitance (Cb), and the wave control resistances Rd and Re[11][12].

v(t)=

(𝑒 𝑒 ) --------------4.1

Where

----------------------------------4.2

--------------------------------------------4.3

Figure4.1 Represent the Voltage Vs Time wave generated by impulse generator which act as lightning voltage

source

Figure4.2 Represent the Current Vs Time wave generated by impulse generator which act as lightning current

source

31

The graphical representation in figure4.1 and 4.2 are the voltage and current

waveform occur by the pulse generator. The RMS value of voltage is 4831 MV occurring in

the system which acts as lightning production in the system. These are just a pulse wave

produced in the system to make the system faulty due to overvoltage occur in the system just

like the occurrence of lightning.

4.3 SIMULATION CRITERIA

The simulation criteria are conducted by creating the model in the

MATLAB\Simulink. The variation in voltage and currents occur in the system which show us

the different simulations regarding the type of model used for evaluating the lightning

arrestors performance in the system. For comparing the simulations regarding the evaluation

of arrestor we develop two similar models, one by using arrestor and another without using

arrestor. From this we come to know about the performance of arrestor in the system.

4.3.1 SWITCHING OVERVOLTAGE

The increase in transmission voltage needs to fulfil the requirement of increase

transmission powers, switching surges have become the main factor for designing of

insulation for the transmission line. In the meantime the lightning overvoltage which is a

source of external overvoltage develops across the system comes as a secondary factor in the

transmission line protection.

In our dissertation we are comparing the two models of transmission line on which

switching overvoltage develops. First model is constructed by using the arrestor and second

without using arrestor. In these models when switching overvoltage occurs, we see the rate of

change of current and voltage develop across the system and the variation result carried out in

the system by using arrestor and without using arrestor.

4.3.1.1 SWITCHING OVERVOLTAGE ACROSS COMPENSATION

DEVICES


In this system when there is any switching operation when occur, there is no arrestor

present in the system. We have calculated the different values of RMS voltage and current in

the sending, midpoint and at the receiving end of the transmission line.

32

Table 4.1 switching overvoltage without using arrestor

RMS

Voltage at

sending

end ( )

RMS

Current at

sending

end ( )

RMS

Voltage at

midpoint

( )

RMS

Current at

midpoint

( )

RMS

Voltage at

receiving

end ( )

RMS

Current at

receiving

end ( )

Time frame

(T)

6.026𝑒 358.4 6.529𝑒 501.5 1.074𝑒 348.6 0.01

6.026𝑒 358.4 6.529𝑒 501.5 1.074𝑒 348.6 0.02

1.687𝑒 192.9 5.119𝑒 7775 8551 330.2 0.03

6.677𝑒 29.18 3.073𝑒 1.752𝑒 1.89𝑒 341.9 0.04

9.026𝑒 60.92 1.621𝑒 1.771𝑒 2.011𝑒 332.6 0.05

3.496𝑒 408.6 4.944𝑒 583.9 3.679𝑒 903.7 0.06

2.005𝑒 376.1 3.864𝑒 1456 1.159𝑒 920 0.07

3.486𝑒 350 2.463𝑒 1508 4.288𝑒 2227 0.08

3.171𝑒 401.5 3.986𝑒 1948 4.241𝑒 1700 0.09

3.014𝑒 322 1.461𝑒 2459 5.973𝑒 2270 0.10

Figure4.3 Voltage Vs Time and Current Vs Time waveform of the shunt reactor at the sending end of

transmission line, switching overvoltage without using arrestor

Figure4.4 Voltage Vs Time and Current Vs Time waveform of the series capacitor at the midpoint of

transmission line,switching overvoltage without using arrestor

33

Figure4.5 Voltage Vs Time and Current Vs Time waveform of the shunt reactor at the receiving end of

transmission line,switching overvoltage without using arrestor

These are the graphical representation of voltage and current waveforms at the sending

end, midpoint and the receiving end of the 200 Km transmission line. These waveforms are

showing the variation across the compensated devices when there is switching fault occur in

the system.

BY USING ARRESTOR

In this system when there is any switching operation when occur, there is arrestor present

in the system. We have calculated the different values of RMS voltage and current in the

sending, midpoint and at the receiving end of the transmission line.

Table 4.2 Switching overvoltage by using arrestor

RMS

Voltage at

sending end

( )

RMS

Current at

sending

end ( )

RMS

Voltage at

midpoint

( )

RMS

Current at

midpoint

( )

RMS

Voltage at

receiving

end ( )

RMS Current

at receiving

end ( )

Time

frame (T)

4.852𝑒 3.971𝑒 3.985𝑒 6.861𝑒 175.7 0 0.01

1.085𝑒 1.228𝑒 2.617𝑒 5.091𝑒 1.75𝑒 2.866𝑒 0.02

1.165𝑒 4.121𝑒 1.785𝑒 2.477𝑒 1.663𝑒 2.234𝑒 0.03

4.209𝑒 3.292𝑒 8421 1.215𝑒 4.193𝑒 2.734𝑒 0.04

5.78𝑒 2.551𝑒 1837 1.064𝑒 5.337𝑒 4.707𝑒 0.05

4.018𝑒 3.218𝑒 1.205𝑒 7.495𝑒 4.377𝑒 2.331𝑒 0.06

1.162𝑒 3.775𝑒 2.1𝑒 8.536𝑒 1.337𝑒 4.046𝑒 0.07

1.486𝑒 8.208𝑒 2.758𝑒 7.049𝑒 1.662𝑒 2.181𝑒 0.08

3.607𝑒 1.462𝑒 3.144𝑒 4.951𝑒 4.167𝑒 1.993𝑒 0.09

5.595𝑒 4.979𝑒 3.254𝑒 2.763𝑒 4.736𝑒 1.198𝑒 0.10

34


transmission line, switching overvoltage by using arrestor


transmission line,switching overvoltage by using arrestor

Figure4.8 Voltage Vs Time and Current Vs Time waveform of the shunt reactor at the receivingend of

transmission line,switching overvoltage by using arrestor

35

These are the graphical representation of voltage and current waveforms at the

sending end, midpoint and the receiving end of the 200 Km transmission line. These

waveforms are showing the variation across the arrestor attached in parallel to the

compensated devices the voltage and current when there is switching fault occur in the

system.

4.3.2 LIGHTNING OVERVOLTAGE

Lighting can change huge damage to low voltage installation. These installations

include high rise buildings, communication lines and equipment’s and other similar facilities.

Lighting may travel on power lines and enter these installations through power lines. So we

have constructed a transmission line on which the lightning will fall. Just like the switching

case we have built the model by using surge arrestor and without using surge arrestor across

the transmission line. For more modification we have inserted the lightning which is

produced by impulse generator (subsystem) on the various positions on the transmission line.

For understanding about the effect of lightning occurrence in the system we are

considering two cases in which we are falling lightning at different position on the

transmission line. After falling the lightning on the transmission line we consider two cases

with and without arrestor to analysis the effect of lightning occurrence in the system.

4.3.2.1 OCCURANCE OF LIGHTNING BEFORE SERIES CAPACITOR


In this system when there is any lightning operation occur before series capacitor, there is

no arrestor present in the system. We have calculated the different values of RMS voltage and

current in the sending, midpoint and at the receiving end of the transmission line. When there

is no arrestor present in the system the voltage and current develop by the lightning will

passes through the compensated devices and damage the compensated system attached across

the system and make the system faulty.

36

Table 4.3 Overvoltage before series capacitor without using arrestor

RMS

Voltage at

sending

end ( )

RMS

Current at

sending

end ( )

RMS

Voltage at

midpoint

( )

RMS

Current at

midpoint

( )

RMS

Voltage at

receiving

end ( )

RMS

Current at

receiving

end ( )

Time frame

(T)

2.663𝑒 13.36 11.11 1477 4545 6.308 0.01

8195 8.514 15.95 432.1 5029 0.6098 0.02

5071 5.484 2.856 289.6 512.1 3.333 0.03

3229 4.081 3.444 723.8 66.07 3.716 0.04

1727 2.389 3.533 1081 118.6 3.629 0.05

1075 2.857 1.27 1298 2339 0.7514 0.06

1390 0.606 0.0435 1430 2183 1.544 0.07

4097 0.1562 0.1145 1394 4387 1.537 0.08

3788 2.118 1.614 1269 5609 2.029 0.09

4571 3.722 4.279 991.2 2369 2.514 0.10


transmission line,Lightning overvoltage before series capacitor without using arrestor



37





showing the variation across the compensated devices the voltage and current when there is

lightning occur in the system before series capacitor attached to the system.

BY USING ARRESTOR


arrestor present in the system. We have calculated the different values of RMS voltage and

current in the sending, midpoint and at the receiving end of the transmission line.

Table 4.4 Lightning overvoltage before series capacitor by using arrestor

RMS

Voltage at

sending end

( )

RMS

Current at

sending

end ( )

RMS

Voltage at

midpoint

( )

RMS

Current at

midpoint

( )

RMS

Voltage at

receiving

end ( )

RMS

Current at

receiving

end ( )

Time frame

(T)

2.663 𝑒 3.804 𝑒 1477 1.911𝑒 1.536𝑒 4546 0.01

8191 9.367𝑒 432.1 3.968𝑒 2.435𝑒 5030 0.02

5071 3.667𝑒 289.6 8.02𝑒 0 512.2 0.03

3230 5.843𝑒 723.8 6.292𝑒 0 66.03 0.04

1726 1.429𝑒 1081 3.217𝑒 0 118.7 0.05

1075 7.483𝑒 1298 2.995𝑒 5.695𝑒 2338 0.06

1391 3.006𝑒 1430 3.783𝑒 1.826𝑒 2183 0.07

4098 6621𝑒 1394 1.07𝑒 2.609𝑒 4387 0.08

3785 1.626𝑒 1269 9.775𝑒 5.771𝑒 5611 0.09

4571 2.033𝑒 9912 4.225𝑒 1.104𝑒 2370 0.10

38


transmission line,Lightning overvoltage before series capacitor by using arrestor







39


compensated devices when there is lightning occur in the system before series capacitor

attached to the system.

4.3.2.2 OCCURANCE OF LIGHTNING AFTER SERIES CAPACITOR


In this system when there is any lightning operation occur after series capacitor, there is

no arrestor present in the system. We have calculated the different values of RMS voltage and


Table 4.5 Lightning overvoltage after series capacitor without using arrestor

RMS

Voltage at

sending

end ( )

RMS

Current at

sending

end ( )

RMS

Voltage at

midpoint

( )

RMS

Current at

midpoint

( )

RMS

Voltage at

receiving

end ( )

RMS

Current at

receiving

end ( )

Time frame

(T)

4.68𝑒 694 652.5 7.005𝑒 1.517𝑒 59.11 0.01

3.424𝑒 1473 1438 5.931𝑒 2.565𝑒 481 0.02

1.69𝑒 1908 1897 4.259𝑒 2.527𝑒 971.6 0.03

3.05𝑒 2070 2053 2.295𝑒 1.855𝑒 1376 0.04

6.973𝑒 2001 1986 2.841𝑒 9.951𝑒 1629 0.05

1.631𝑒 1741 1731 1.562𝑒 9828 1707 0.06

7.488𝑒 1482 1461 3.141𝑒 2.41𝑒 1462 0.07

2.742𝑒 1058 1085 4.405𝑒 1.62𝑒 1622 0.08

2.496𝑒 657.7 615.1 5.247𝑒 2.647𝑒 574.6 0.09

2.322𝑒 59.56 92.85 5.597𝑒 3.174𝑒 128.6 0.10


transmission line,Lightning overvoltage after series capacitor without using arrestor

40







showing the variation across the compensated devices when there is lightning occur in the

system after series capacitor attached to the system

BY USING ARRESTOR


arrestor present in the system. We have calculated the different values of RMS voltage and


41

Table 4.6 Lightning overvoltage after series capacitor by using arrestor

RMS

Voltage at

sending

end ( )

RMS

Current at

sending

end ( )

RMS

Voltage at

midpoint

( )

RMS

Current at

midpoint

( )

RMS

Voltage at

receiving

end ( )

RMS

Current at

receiving

end ( )

Time frame

(T)

1.647 𝑒 1.401𝑒 143 1.61𝑒 2.61𝑒 1.387𝑒 0.01

1.091𝑒 1.559𝑒 3.477 1.494𝑒 4.361𝑒 1.947𝑒 0.02

5.95𝑒 1.082𝑒 0.0001876 1.228𝑒 5.914𝑒 7.96𝑒 0.03

2.955𝑒 6.865𝑒 1.77𝑒 8.485𝑒 5.219𝑒 1.547𝑒 0.04

4498 9.141𝑒 6.029𝑒 4.162𝑒 3.72𝑒 6.871𝑒 0.05

2.02𝑒 3.753𝑒 1.149𝑒 1603 1.825𝑒 2.334𝑒 0.06

3.844𝑒 3.515𝑒 1.785𝑒 4.061𝑒 2978 1.017𝑒 0.07

2.636𝑒 2.269𝑒 1.615𝑒 7.376𝑒 4.676𝑒 6.333𝑒 0.08

4.719𝑒 1.002𝑒 5.52𝑒 9.965𝑒 5.051𝑒 3.011𝑒 0.09

7.01𝑒 3.937𝑒 1.094𝑒 1.16𝑒 4.403𝑒 3145𝑒 0.10


transmission line,Lightning overvoltage after series capacitor by using arrestor



42






compensated devices when there is lightning occur in the system after series capacitor

attached to the system

4.4 SIMULATION RESULTS

Case 1- Switching overvoltage across compensation devices

Table4.7 Comparison between Switching overvoltage with arrestor and without arrestor model

S.No Without Arrestor With Arrestor

1

Sending end Voltage Vs Time and Current Vs

Time waveforms

Average RMS Voltage ( )= 1.983 𝑒 V

Average RMS Current ( )=285.8 A


Time waveforms

Average RMS Voltage ( )= 92020 V

Average RMS Current ( )=3.0489 𝑒 A

43

2

Midpoint Voltage Vs Time and Current Vs

Time waveforms




Time waveforms



3

Receiving end Voltage Vs Time and Current

Vs Time waveforms



Receiving end Voltage Vs Time and Current Vs

Time waveforms


Average RMS Current ( )= 4.7192 𝑒 A

44

Case 2- Occurrence of lightning before series capacitor

Table4.8 Comparison between lightning overvoltage before series capacitor with arrestor and without arrestor

model


1


Time waveforms

Average RMS Voltage ( )= 3314.56V



Time waveforms

Average RMS Voltage ( )= 5976.8 V


2


Time waveforms

Average RMS Voltage ( )= 4.4214 V



Time waveforms



3


Vs Time waveforms




Time waveforms


Average RMS Current ( )= 2716.193A

45

Case 3- Occurrence of lightning before series capacitor

Table4.9 Comparison between lightning overvoltage after series capacitor with arrestor and without arrestor

model


1


Time waveforms


Average RMS Current ( )=2863.556A


Time waveforms

Average RMS Voltage ( )= 20229 V


2


Time waveforms


Average RMS Current ( )=847261 A


Time waveforms


Average RMS Current ( )=85068.70A

3


Vs Time waveforms




Time waveforms


Average RMS Current ( )= 7.978 𝑒 A

46

From all these comparisons we concluded that in case of arrestor models as long as

the voltage develops across the compensated devices is above the protective level then all the

current is flowing into the MOV. The flow of current is null through compensated devices

when the voltage passes below the protective level because the MOV offers a high resistance.

But in the absence of arrester model all the high voltage and current will passes through the

compensated device which will either turn off the system or damage the whole compensated

system because the compensated devices allow the high voltage and current to pass through

them as a low resistive path to flow.

47

CHAPTER 5

CONCLUSION AND FUTURE SCOPE

5.1 CONCLUSION

In our dissertation, we have design the model of transmission line on which we

evaluated the performance of lightning arrestor installed in the system. All the simulation is

carried out in MATLAB/Simulink. We have designed a transmission model in which we have

analysed the switching overvoltage occurrence with or without the help of surge arrestor and

compared their results and evaluated the performance of arrestor across the line.

We have also analysed the system when lightning overvoltage strikes the system. For

simulation of lightning, we used a transfer impulse function block as impulse generator which

induces a large voltage across the transmission line just like the occurrences of lightning in

the nature (in the Simulink). All the simulations were carried out by inserting the transfer

function block at different points on the transmission line and then comparisons were made.

Simulation results are compared by using arrestor or without using arrestor model. In the last

we concluded that it is preferable to use arrestor across the line to protect the compensated

devices across the system because the arrestor protective devices operate immediately in

order to remove the heavy overvoltage to pass through the compensated devices. The flow of

current is null through compensated devices when the voltage passes below the protective

level because the arrestor offers a high resistance.

5.2 FUTURE SCOPE

By considering the various factors corresponding to the lightning and switching

overvoltage’s we can use this extra energy for harvesting purposes. This is a very difficult

task but not impossible. As we come to know the various parameters on which lightning

depends we can develop a control system which can control this extra energy source for

harvesting purpose.

48

REFERENCES

[1] Bui-Van Q., E. Portales, D. McNabb, and V. Gajardo, “Transient Performance of 500-kV

Equipment for the Chilean Series-Compensated Transmission System,” Proceedings of the

international Conference on Power System Transients (IPST’03), pp. 1-6, October 2008

[2] Chanaka M., KusumShanthi, RanjitPerera “Modeling of Power Transmission Lines for

Lightning Back Flashover Analysis (A Case Study: 220kV Biyagama-Kotmale Transmission

Line)” 2011 IEEE 6th

International Conference on Industrial and Information Systems, ICIIS

2011, Aug. 16-19, 2011, Sri Lanka

[3] Christodoulou1 C.A., G. Perantzakis, G.E. Spanakis, P. Karampelas”Evaluation of

lightning performance of transmission lines protected by metal oxide surge arrestors using

artificial intelligence techniques”2006, Journal of Energy Systems The final publication is

available at www.springerlink.com

[4] Dingxie Gu, Dai Min, He Huiwen, High Voltage Institute China State Grid Electric

Power Research Institute Wuhan, China “Lightning Protection of 1000 kV AC Power

Transmission Lines and Substations” 2011 IEEE, 7th

Asia-Pacific International Conference

on Lightning, November 1-4, 2011, Chengdu, China

[5] Ekonomou L., I.F. Gonos, D.P. Iracleous, I.A. Stathopulos”Application of artificial neural

network methods for the lightning performance evaluation of Hellenic high voltage

transmission lines” Electric Power Systems Research 77 (2007) National Technical

University of Athens, School of Electrical and Computer Engineering, High Voltage

Laboratory, 9 IroonPolitechniou St., Zografou, GR 157 80 Athens, Greece

[6] Ekonomou L, P Karampelas, V Vita and G E Chatzarakis “Evaluation of the probability

of arrestor failure in a high-voltage transmission line using a Q learning artificial neural

network model”© 2011 IOP Publishing Ltd Printed in the UK & the USA 27

49

[7] Eguzo C.V, E.I Igweonu and B.J Robert “SELECTION CRITERIA FOR LIGHTNING

ARRESTOR SYSTEMS IN NIGERIA” International Journal of Advancements in Research

& Technology, Volume 2, Issue4, April-2013, Electrical Electronics Engineering Department

AkanuIbiam Federal Polytechnic, Unwana

[8] Gupta B.R. “power system analysis and design” book,first edition 2005

[9] Henschel S., L. Kischner, and M. C. Lima, “Transient Recovery Voltage at Series

Compensated Transmission Lines in Piauí, Brazil,” Proceedings of the International

Conference on Power System Transients (IPST’05), pp. 1-6, June 2005

[10] Johar Dalinai, TitikKhawa Abdul Rahman, Ismail Musirin, Member, IEEE”Artificial

Neural Network Based Technique for Lightning Prediction”The 5th

Student Conference on

Research and Development –SCO 11-12 December 2007, Malaysia

[11] Jayaraju M., B. Prabhakar. Generation of unidirectional and bidirectional oscillatory

switching impulse voltages.in: Proceeding of the 9th

International Symposium on High

voltage Engineering, Graz Technical University, Austria, 1995

[12] Kannan S.,M.Tech,N.Rao.Generator loading limits for impulse testing low inductance

windings, in: Proceeding of the Institution of Electrical Engineers, 1957,122(5): 535-538

[13] Nekoubin Abdolamir “Simulation of series compensated transmission line protected

with Mov” World Academy of Science, Engineering and Technology, Vol:5 2011-10-28,

Electrical Engineering Department, Islamic Azard University Najaf Abad Branch,

International Scholarly and Scientific Research & Innovation 5(10)2011.

[14] Omidiora M.A.,”PERFORMANCE ANALYSIS OF LIGHTNING OVERVOLTAGE

ON MEDIUM VOLTAGE DISTRIBUTION LINE EQUIPPED WITH COVERED

CONDUCTORS”, 2009, 2nd

international conference on adaptive sciences and technologies.

50

[15] Rodriguez-Sanabria D., Student Member, IEEE, C. Ramos-Robles, UPRM Graduate

Student, L. Orama- Exclusa, Member, IEEE”Lightning and Lightning Arrestor Simulation in

Electrical Power Distribution Systems”

[16] Ray Subir “electrical power system concepts, theory and practice” book, PHI Learning

private Limited 2012

[17] TarilanyoAfa John”Selection of Lightning Arrestor in the Niger Delta Environment”

International Journal of Innovation and Applied Studies ISSN 2028-9324 Vol. 3 No. 1 May

2013, Department of Electrical Engineering, Niger Delta University, PMB 71 Wilberforce

Island, Bayelsa state, Nigeria

[18] Vladimir A. Rakov”Lightning Discharge and Fundamentals of Lightning Protection”

Journal of Lightning Research, 2012,Department of Electrical & Computer Engineering,

University of Florida, Gainesville, FL, USA

[19] Wang Young,”SIMULATION OF LINE SURGE ARRESTOR FOR LIGHTNING

PROTECTION IN 10KV TRANSMISSION LINE”,Electricity distribution. 2008 CICED

2008, China International Conference,10-13 dec 2008

[20] Zhang Xuewei, Lin Dong, Jinliang He*, Shuiming Chen and RongZeng “Study on the

Effectiveness of Single Lightning Rods by a Fractal Approach” Lightning Research, 2009

State Key Lab of Power Systems, Department of Electrical Engineering, Tsinghua

University, Beijing 100084, China

51

APPENDIX

GLOSSARY OF TERMS

1. VOLTAGE SURGE: Any sudden excessive rise in the voltage that may be

dangerous to the electrical equipment’s of an installation is known as voltage surge.

2. LIGHTNING: Lightning is a huge spark which is due to the electrical discharge

taking place between the clouds, within the same cloud and between the cloud and

ground.

3. A STROKE LIGHTNING: A stroke lightning is characterised by the comparatively

long time to produce discharge. It strikes the highest and most sharply pointed object

in the neighbourhood.

4. B STROKE LIGHTNING: B stroke lightning is characterised by its rapidity. It

ignores the tall objects and reaches the ground in the random manner. B stroke is most

dangerous lightning stroke.

5. EARTHING SCREEN: Earthing screen consists of a network of copper conductors,

earthed at least on two points, over all the electrical equipment in the substation.

6. EARTH WIRE: An earth wire is a form of lightning protection using a conductor or

conductors, well-grounded at regular intervals, preferable at each support and attached

from support to support above the transmission line.

7. LIGHTNING ARRESTOR: Lightning arrestor limits the duration and amplitude of

the follow current.

8. SURGE ABSORBER: Surge absorber reduces the steepness of the wave front of a

particular surge.

52

ABBREVIATIONS

LFC : LOAD FREQUENCY CONTROL

MATLAB : MATRIX LABORATORY

PI : PROPORTIONAL-INTEGRAL

PID : PROPORTIONAL-INTEGRAL-DERIVATIVE

AC : ALTERNATING CURRENT

AGC : AUTOMATIC GENERATION CONTROL

ACE : AREA CONTROL ERROR

HVDC : HIGH VOLTAGE DIRECT CURRENT

EHVAC : EXTRA HIGH VOLTAGE ALTERNATING CURRENT

HIL : HARDWARE-IN-LOOP

SSE : STEADY STATE ERROR

MOV : METAL OXIDE VARISTOR

TSR : TOTAL SURGE REACTOR

ANN : ARTIFICIAL NEURAL NETWORK

evaluation of lightning arrestor by using matlab

Documents